1. Field of the Invention
The present invention relates to the use of an immunogenic composition comprising a porcine circovirus type 2 (PCV2) antigen for treatment of several clinical manifestations (diseases). Preferably, those clinical manifestations are associated with a PCV2 infection. More particularly, the present invention is concerned with an immunological composition effective for providing an immune response that reduces, or lessens the severity, of the clinical symptoms associated with PCV2 infection. Preferably, the immunological composition comprises a recombinantly produced antigen of PCV2. More preferably, the PCV2 antigen is a recombinantly produced protein encoded by one of the open reading frames (ORFs) in the PCV2 genome. Still more preferably, the antigen is PCV2 ORF2 protein. Most particularly, the present invention is concerned with an immunological composition effective for treatment of clinical symptoms associated with PCV2 infections in swine receiving the immunological composition, and wherein the composition comprises the protein expressed by ORF2 of PCV2. Another aspect of the present invention is the use of any of the compositions provided herewith as a medicament, preferably as a veterinary medicament, even more preferably as a vaccine. Moreover, the present invention also relates to the use of any of the compositions described herein, for the preparation of a medicament for reducing or lessening the severity of clinical symptoms associated with PCV2 infection. Preferably, the medicament is for the prevention of a PCV2 infection, even more preferably in swine. A further aspect of the present invention relates to a process for the production of a medicament, comprising an immunogenic composition of PCV2 for the treatment of several clinical manifestations.
2. Description of the Prior Art
Porcine circovirus type 2 (PCV2) is a small (17-22 nm in diameter), icosahedral, non-enveloped DNA virus, which contains a single-stranded circular genome. PCV2 shares approximately 80% sequence identity with porcine circovirus type 1. (PCV1). However, in contrast with PCV1, which is generally non-virulent, swine infected with PCV2 exhibit a syndrome commonly referred to as Post-weaning Multisystemic Wasting Syndrome (PMWS). PMWS is clinically characterized by wasting, paleness of the skin, unthriftiness, respiratory distress, diarrhea, icterus, and jaundice. In some affected swine, a combination of all symptoms will be apparent while other affected swine will only have one or two of these symptoms. During necropsy, microscopic and macroscopic lesions also appear on multiple tissues and organs, with lymphoid organs being the most common site for lesions. A strong correlation has been observed between the amount of PCV2 nucleic acid or antigen and the severity of microscopic lymphoid lesions. Mortality rates for swine infected with PCV2 can approach 80%. In addition to PMWS, PCV2 has been associated with several other infections including pseudorabies, porcine reproductive and respiratory syndrome (PRRS), Glasser's disease, streptococcal meningitis, salmonellosis, postweaning colibacillosis, dietetic hepatosis, and suppurative bronchopneumonia. However, research thus far has not confirmed whether any of these clinical symptoms are in fact, the direct result of a PCV2 infection. Moreover, it is not yet known whether any of these clinical symptoms can be effectively reduced or cured by an active agent directed against PCV2.
Current approaches to treat PCV2 infections include DNA-based vaccines, such as those described in U.S. Pat. No. 6,703,023. However, such vaccines have been ineffective at conferring protective immunity against PCV2 infection or reducing, lessening the severity of, or curing any clinical symptoms associated therewith. Moreover, vaccines described in the prior art were focused solely on the prevention of PCV2 infections in swine, but did not consider any further medical use.
Accordingly, what is needed in the art is an immunogenic composition for the treatment of several clinical manifestations. Further, what is needed in the art is an immunological composition which confers protective immunity against PCV2 infection but which can also be used to treat existing clinical symptoms associated with PCV2 infection.